RadioBanter - View Single Post - inexpensive analog audio pitch (frequency?) meter or schematic/ plans for one?

William Sommerwerck[_2_]

wrote:

I know that a given sound has a fundamental tone and overtones,
and it would have to detect the fundemantal tone (like a guitar tuner).

There's no need to "detect" the fundamental. The device would simply look
for zero crossings, which are the same regardless of the presence or absence
of harmonics.

In fact, I'm reasonably (but not completely) sure a PLL would work with a
non-sine signal.